The present disclosure relates in general to the field of electronic devices and more specifically to a system and method for using a surrogate component in shock or vibration testing.
Shock and vibration testing is performed on computer systems and system components such as hard drives, liquid crystal displays (LCDs), compact disk (CD) drives, floppy drives, and other peripheral components, in order to determine whether the systems and components can withstand anticipated shock and vibration events. Testing often is performed on assembled systems as well as on individual components. System testing often consists of securing a test system (with components installed within) to a programmable shock table and selectively inducing a desired shock to the system. The force delivered to the system may be measured using an accelerometer.
Testing individual component, which is sometimes referred to as xe2x80x9cstand-alone testingxe2x80x9d often consists of securing a component to a shock table and delivering a selected shock or vibration to the component. The component is then tested to determine whether the delivered shock or vibration has damaged the component. If the component is undamaged, the selected shock is increase incrementally and the component is re-tested. This process is repeated until the component fails, thereby determining the shock level which a component can withstand. This is sometimes referred to as a component""s level of fragility.
The testing of assembled systems presents a number of problems. One problem occurs in the shock testing of systems with installed components. Typically, an accelerometer is secured to a component to measure the shock delivered to the component. This testing is performed in order to determine the shock experienced by a component when the test system experiences a particular shock. However, this measurement is often inaccurate, as the system itself may absorb, dampen, amplify, or otherwise distort the force experienced and recorded by the accelerometer attached to the component. Accordingly, components from different suppliers installed in identical systems may have different responses to the same stimuli delivered to the system.
Also, the component within the test system experiences a complex waveform, as opposed to the ideal waveform experienced by the stand-alone test of the component. The correlation of system level response to the stand-alone response (or device fragility level) is often difficult to make. Part of the problem is from the difficulties that the time domain data presents in comparative analysis. The comparison of complex waveform from the system test to the stand-alone ideal waveform from the stand-alone test is not a direct comparison. Usually the amplitudes of each waveform were compared to determine if the drive in the system had received a shock that exceeded the drive""s own fragility established in stand alone testing. In most cases a fundamental waveform cannot be gleaned from this data. There are usually many amplitudes along the time domain of the complex waveform generated by the system test and there is not a reliable way to determine which amplitudes represent sufficient energy to damage a component.
Yet another problem associated with testing components is that system testing may result in component failure, destroying the component. Accordingly, this testing requires significant resource allocation.
Therefore, a need has arisen for a system and method for comparing the shock response from stand alone component tests and system shock and vibration tests.
A further need has arisen for a system and method for performing shock and vibration testing of systems that reduces resource requirements.
A further need has arisen for a system and method for accurately measuring the shock experienced by a component during system shock and vibration testing.
In accordance with teachings of the present disclosure, a system and method are described for using a surrogate component in shock and vibration testing that substantially reduces the problems and difficulties associated with prior systems and methods for shock and vibration testing of components and systems.
The disclosure includes a surrogate component for shock testing a housing with exterior dimensions, mass, and a center of gravity approximately the same as the exterior dimensions, mass, and center of gravity of a counterpart component. The housing also has a stiffness greater than the counterpart component and has an interface for securing a sensor. More particularly, the counterpart component may be a hard drive and the housing may be constructed from a molybdenum material.
The present disclosure also describes a method for testing a computer system that includes obtaining surrogate component shock data from an accelerometer that is secured to a surrogate component installed within a test system. The surrogate component shock data is then converted to shock response spectrum (SRS) data. The surrogate component SRS data is then compared to SRS data from stand alone counterpart component SRS data.
The present disclosure contains a number of important technical advantages. One technical advantages is converting shock response data into the shock response spectrum. This allows for a meaningful comparison of the shock response from stand alone component tests and system testing.
Another technical advantage of the present disclosure is the introduction of a surrogate component in system testing. The use of a surrogate component reduces resource requirements by eliminating the need to use components which may be damaged during testing. The use of surrogate components also increases the accuracy of the data collected by eliminating the distorting effects of actual components because the increased stiffness of the surrogate component assures that the acceleration measured internally is the same as the acceleration delivered externally to the surrogate component.